Glow-discharge lamp



Sept. 24, 1935. v F. SCHROTER El AL 2,

' GLOW DISCHARGE LAMP Filed June 26, 1928 w #lllk k I i INVENTQR rmz seamen By on cmusv Q14 Adam,

ATTO E Y recording as in Patented Sept. 24, 1935 Fritz Schriiter and Otto many, assignors to Tele Drahtlose Telegraphic Schriever, Berlin, Gerfunken Gesellschaft fiir m. b. 11., Berlin, Germany, a corporation of Germany Application June 26, 1928, Serial No. 288,326

In Germany July 8, 1927 2 Claims. (Cl. 176-124) The glow-discharge lamp has been suggested for quite a number of purposes in connection with the recording of variable or changing actions and events, for instance, for photographic the glow-light oscillograph, for picture telegraphy and the speaking film further for subjective visualization as in television work and other purposes.

The glow-discharge lamps heretofore known involve the disagreeable propertythat the potential required for operation must lie beyond a certain comparatively high value known as the flashing or ignition potential, in order that the lamp may be caused to luminesce. Also, the currents obtainable are comparatively low, while the potential variations required for the control of certain current variations are comparatively high.

Now, these inconvenient features are obviated by the disclosures of the present invention. The basic feature of the latter resides in that the cold cathode heretofore customarily used in the glowdischarge lamp is replaced by a heated cathode, with the result that emission of electrons will be brought about in the presence of comparatively low potentials. The sensitiveness or responsiveness of the "lamp, that is, the dependence of the current upon the terminal potential, is considerably increased, while the discharge current, by suitable dimensioning of the hot filament furnishing the electrons and the addition of positive ionization can be chosen of any desired high value. The filament is most suitably mounted in the rear of a diaphragm in such a manner that the light issuing therefrom will not disturb the recording work done by the glowdischarge light, looked at from an optical standpoint. The comparatively small aperture in the diaphragm which otherwise shuts oif the discharge space completely, furnishes a high current and luminous density, and this is of essential importance for the practical use of the lamp; and in front of the diaphragm, provided the conditions of pressure and current density are suitably chosen, there is produced a sort of secondary cathode possessing and exhibiting bright glow-discharge phenomena with marked actinic and intensive radiation. The diaphragm can be mounted in a perfectly insulated manner, or it may be grounded or else again it may be in conductive relationship with the cathode directly or by way of an auxiliary potential. For the punctiform concentration of the glow-discharge light all such means as have been known in the art may be employed, also the shape of the anode sudden and abrupt, as in the old scheme.

may be conveniently chosen from among the forms disclosed in earlier publications. The filament, as in modem amplifier tubes, is suitably made from a sort of material which even in the presence of a dull redness emits suflicient elec- 5 runs.

The invention preferred forms wherein:

Fig. 1 represents a glow lamp with the cathode 10 mounted concentric to the diaphragm;

Fig. 2 represents a modified form of Fig. 1; and

Fig. 3 represents a still further modification wherein an auxiliary electrode is employed.

To now refer to the embodiment of the glowdischarge lamp herein disclosed by way of example in Fig. 1. Cathode c has here the form of a cylindrical spiral or helix, for instance, and it is mounted concentric with relation to the aperture of the diaphragm b. The anode a is 29 located beyond the diaphragm.

The potential to be recorded, in line with previous practice, for instance, by way of a transformer Tr with the optional insertion of a battery A may be fed to the glow-discharge lamp 25 between anode and cathode, as diagrammatically shown in Fig. 2, or else the diaphragm or an auxiliary electrode mounted between anode and cathode and suitably biased by means of battery A may be used to act as a controlling electrode 30 similar to the grid in amplifier tubes, as illustrated in Fig. 3. This latter arrangement offers the particular advantage that for controlling or operating the lamp a minimum amount of energy will be sufficient, while the illuminating energy of the lamp is derived, from a distinct potential source A. The control electrode is suitably insulated on the side turned towards the hot filament by that its surface on this side is covered, for instance, with a mica layer m. Such grid-like control is feasible in the subject matter herein disclosed, contradistinct from what is true of glow-discharge lamps having a cold cathode, because the imtiation of the glow-discharge is very gradual and progressive, and not Another disadvantage, namely the disagreeable diiference between ignition potential and extinction potential, plays no part in the present invention.

Having now described our invention what we claim and desire to secure by Letters Patent is:

1. In a glow lamp construction, an anode member having a central opening therein, a spiral cathode member arranged concentric with the is illustrated in several of its by the accompanying drawing,

opening in said anode member, an evacuated chamber enclosing both said anode and cathode members, means for heating the said cathode member, a diaphragm serving as an auxiliary electrode positioned between said anode and cathode members, an insulating medium on the surface of said diaphragm toward said cathode, means for biasing said auxiliary electrode with a constant source of potential, means for impressing signals to be recorded across said cathode and auxiliary electrode, and a source of constant potential connected between said anode and cathode whereby signal potentials to be recorded are converted into light intensities of 'values varying in proportion to the strength of received signals.

2. In a glow lamp construction, an apertured anode member, a cathode member centrally arranged with respect to the aperture in the anode, means for heating the cathode member, a diaphragm interposed between the anode member and the cathode member and having an aperture therein axially aligned with respectto the cathode ing. the anode at fixed potential relative to the 10 cathode, and means for applying signaling volt ages to be recorded across the cathode and the auxiliary electrode so that applied voltages are converted into light intensities of values varying in proportion to the intensity of impulses, and an evacuated chamber enclosing all of the electrodes.

FRI'IZ scHRtiTER.

OTTO SCHRIEVER.

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